Electronic Diagnostics LEXUS RX400h 3.3-litre petrol

Tracing and fixing faults in electronic engine management systems

Note: All references in our text and captions to ‘left’ and right’ sides are from the point of view of someone sitting in the car and looking ahead.

Self-charging and plug-in hybrids are, of course, big news today, but back in the mid-2000s this was an area of automotive engineering that was just beginning to emerge in mainstream models.

Toyota/Lexus were early exponents of hybrid vehicles, with the Prius saloon arriving in 1997. They were also pioneers in producing luxury SUV models, with the unitary construction RX introduced in 1993.

The Lexus Hybrid Drive system was offered in the RX400h from June 2005 (in Britain), with the new model incorporating the company’s first four-wheel drive hybrid power train. This model was part of the second-generation RX line-up.

Power was provided by a 3.3-litre V6 petrol engine, plus a high-voltage, high-speed electric motor driving the front wheels through a continuously variable transmission (CVT) and reduction gear set-up, with a separate second electric motor driving the rear wheels. The car could be driven in petrol or electric-drive modes, or with a combination of the two.

This was a high-performance vehicle fo its time, with a zero to 62mph acceleration of